Transmission of information, including analog and digital data, using fiber optic cables has become common as an alternative to conventional wire transmission arrangements. Fiber optic cables have distinct advantages over coaxial cables for video signals, for example, as well as over electrical wiring for transmission of information. It is particularly advantageous to use fiber optic cables to enhance transmission security and to allow an increased number of transmission paths for a given cross-sectional cable area. Fiber optic cables further provide relatively low signal loss for a given transmission distance, which makes it possible to reduce the number of booster stations. Fiber optic cables are also relatively immune from electromagnetic interference.
Fiber optic cables include an inner glass core of very small diameter. The inner glass core, which is appropriately described as a fiber strand, is normally encased in an outer protective ceramic sleeve of a diameter that may be approximately 125 microns compared to a diameter of 8 microns, for example, for a single glass fiber strand. The glass strand and sleeve are surrounded by a silicon cladding as part of a buffer jacket that may include an outer polyurethane covering. The diameter of the jacket may be approximately 5 mm.
The fiber optic cable at its end is mounted in a connector. The connector typically would be supported by a coupling mounted on a panel. A companion fiber optic cable would be mounted in a corresponding connector and arranged in a coupling with the axes of the fiber optic strands in alignment. The ends of the fiber optic strands would engage in abutting relationship at an interface point.
In a typical fiber optic cable environment, the end surfaces of the fiber optic strands at the interface may accumulate dirt and dust particles and other contaminants such as grease. This causes degradation in the amount of light energy that may be transferred through the fiber strands. In the maintenance of fiber optic cable installations, it is known practice to disassemble the connectors at the ends of the fiber optic cable assemblies and to clean the ends of the fiber cable strands with a cleaning device and a cleaning solution.
It is known in the prior art also to polish the end of a fiber optic strand during manufacture. U.S. Pat. Nos. 4,999,955 and 5,463,709, for example, show methods and apparatus for polishing the end of a fiber optic cable and machining the fiber optic cable ends with a spherical end face. Fiber optic cable ends that are machined with a spherical profile, however, tend to develop high stress concentrations at the fiber optic contact points. This may induce cracking of the glass core of the fiber optic cable, which would impair the ability of the cable to transmit light energy in an operating environment in which the cables are subjected to mechanical vibrations, such as a spacecraft environment. Flat cable ends would be preferred in such environments over the spherical ends. The machining and polishing apparatus intended for use in the manufacture of cables with spherical cable ends, however, cannot be used in polishing a flat fiber optic strand end.
The prior art includes also optical fiber end surface polishing devices intended for use with cable terminal tips with flat ends, examples of which are described in U.S. Pat. No. 5,547,418 and Japanese Patent Publication 55-115009. Such conventional apparatus for machining and polishing flat fiber optic terminal tips are intended, however, primarily for use in the manufacture of fiber optic cables rather than as maintenance tools for polishing fiber optic terminal tips after installation of the fiber optic cables. Typically, such conventional apparatus do not include a simple and feasible means for maintaining the close dimensional tolerances required for most fiber optic cable designs.
A disadvantage of some known polishing tools for fiber optic terminal tips is the necessity to disassemble the fiber optic cable itself in order to carry out fiber optic terminal tip polishing as part of the manufacturing or the maintenance procedure.